The continued prevalence of nosocomially acquired infections, and concomitant clinical and epidemiologic interest in typing isolates, have resulted in many large clinical laboratories using molecular epidemiologic methodologies to investigate the relatedness of clinically isolated micro-organisms. In the Microbiology Service, we are currently evaluating a number of different approaches to molecular strain typing, including plasmid analysis, restriction endonuclease analysis of genomic DNA (REA), pulsed-field gel electrophoresis of genomic DNA (PFGE) and PCR based typing methods. The goal of this projeCt is to develop a co-ordinated battery of typing methods that can be used to provide information on a wide variety of clinically significant micro-organisms.